When Philando Castile, a black man legally carrying a concealed weapon, was shot dead by police during a traffic stop in Minnesota this month for no apparent reason other than that he was armed, it seemed like an obvious case for the National Rifle Association to rally behind. The Second Amendment protects everyone's right to bear arms, not just white people's, right?By the light of the law, the answer is easy: The Constitution prohibits racial discrimination in all rights, including the right to bear arms.